Metal detectors of various configurations are well known and have been successfully used in many diverse applications. For example, metal detectors have become commonplace at airports and other places where the smuggling of firearms, bombs and other dangerous metal objects must be detected. Metal detectors are also commonly used in prospecting and numerous other activities which require the location of lost or unseen metal objects. The detectors used for these purposes, however, are typically sophisticated and complicated devices which are relatively difficult to manufacture, operate and maintain.
In the medical field, there is a particular need for controlling the inadvertent loss of surgical and medical instruments which the present invention recognizes can be accomplished by using a metal detector. Not just any metal detector will suffice for this purpose, however, because most of these losses occur when the instruments are inadvertently discarded along with used bandages, contaminated articles, or soiled linens and clothing. Unfortunately, these losses can be quite costly.
Obviously, the most effective place to detect the inadvertent disposal of surgical and medical instruments is at the point where waste is being collected. Typically, in hospitals, this occurs at hampers and receptacles which are located at various sites throughout the hospital. Moreover, these hampers and receptacles need, at times, to be moveable in order to satisfy the efficiency requirements of the hospital. Further, the detection of discarded surgical and medical instruments should be accomplished without undue disruption of the hospital's routine. For example, it is desirable that the metal detector not yield false alarms when certain non-ferrous materials are discarded, such as aluminum wrapping used for containing certain hospital supplies.
The present invention recognizes that a metal detector can be provided which is operatively adaptable to a hamper or receptacle for determining when a metal object has been placed into the hamper or receptacle. The present invention also recognizes that this detection can be accomplished while ignoring or disregarding the presence of metal objects in the vicinity of the hamper or receptacle until such time as these objects are actually being placed into the hamper or receptacle. It is also recognized by the present invention that a metal detector can be provided which ignores certain non-ferrous metallic waste, such as aluminum wrapping, that is discarded into the receptacle. The present invention further recognizes that a metal detector can be provided which is easily moved with the receptacle and which can be easily maintained.
In light of the above, it is an object of the present invention to provide a metal detector which will detect the passage of a metal object through a predetermined space or passageway that is circumscribed by the detector. Another object of the present invention is to provide a metal detector which will disregard the passage of a nearby metal object unless the object passes through the passageway established by the detector. Yet another object of the present invention is to provide a metal detector which is sufficiently sensitive to detect the passage, through its passageway, of medical and surgical instruments while ignoring the passage of non-ferrous metal material such as aluminum wraps. Still another object of the present invention is to provide a metal detector which has a minimal number of components in order to simplify the maintenance and repair of the detector. Another object of the present invention is to provide a metal detector which is operatively adaptable to mobile hampers or receptacles. Still an additional object of the present invention is to provide a metal detector which is relatively easy to manufacture and which is cost effective.